Size control apparatus



1962 w. R. CARLSEN 3,056,241

SIZE CONTROL APPARATUS Filed March 15, 1961 Z Sheets-Sheet 1 IN VEN TOR. 275k? 2'? Car/3071.

BY W 1 JENZ/Sf W. R. CARLSEN SIZE CONTROL APPARATUS Oct. 2, 1962 I NV EN TOR. 6.4719871 -PM zm LKg Filed March 13, 1961 Oct. 2, 1962 Filed March 15, 1961.

w. R. CARLSEN 3,056,241

SIZE CONTROL APPARATUS 4 Sheets-Sheet 3 :FEHE.

INVENTOR.

Oct. 2, 1962 w. R. 'CARLSEN 3,056,241

SIZE CONTROL APPARATUS Filed March 13, 1961 4 Sheets-Sheet 4 L INVENTOR.

. FCdfZswP IIIWV United States Patent 3,056,241 SIZE CONTROL APPARATUS William R. Carlsen, Huntington Wood, Mich., assignor to Michigan Tool Company, Detroit, Mich., a corporation of Delaware Filed Mar. 13, 1961, Ser. No. 95,116 11 Claims. (Cl. 51-165) The present invention broadly relates to abrasive finishing machines and more particularly to a size control apparatus for automatically dressing the outside diameter of a gear-like abrasive tool or hone adapted to be disposed in meshing relationship with a toothed workpiece to be finished.

Abrasive finishing machines of the general type to which the present invention is applicable are employed in industry for accurately finishing the surfaces of hardened tooth elements such as gear teeth, splines, serrations, and the like. Machines of this type conventionally employ an abrasive impregnated gear-like tool or hone which is rotated in tight meshing relationship with a hardened workpiece having tooth elements thereon. The hone and workpiece are preferably rotated in meshing relationship at crossed axes efifecting a relative abrasive action along the entire face width of the tooth elements on the workpiece providing an effective method for quickly removing nicks and burs on the tooth elements and also for correction of small dimensional inaccuracies such as tooth spacing, involute profile, lead, runout, etc. caused during heat treatment of the workpiece. The correction of such dimension inaccuracies in gears, for example, provides for an improved contact pattern of mating teeth causing a material reduction in the noise level of such gears and obviates, in most instances, the heretofore costly and time consuming practice of matching and lapping gears in pairs.

After prolonged finishing operations, the honing tool progressively wears to the extent that it must be discarded and replaced with a new hone or alternatively, is removed from the machine and trimmed or dressed to the proper configuration and dimensional tolerances. While the honing tools generally employed are of the socalled throw-away type, it has now been found that by dressing the hone at relatively short time intervals, the working life of the hone can be greatly increased and the accuracy and degree of surface finish obtained thereby, can be maintained at a high level throughout the life of the hone.

In the finishing of toothed elements such as gear teeth, for example, the abrasive action between the workpiece and hone automatically maintains the form of the hone and it is only necessary to dress the periphery thereof to restore the correct pitch-circle relationship between the hone and workpiece. In accordance with the preferred practice of the present invention, periodic dressing of the hone is automatically achieved in response to a decrease in the center distance between the hone and a toothed workpiece disposed in tight meshing relationship therewith. The automatic dressing of the hone is achieved in situ obviating the need of removing the hone from the finishing machine as heretofore has been the practice. In addition, the dressing of the hone is achieved automatically and in controlled preselectable increments so as to maintain optimum dimensional accuracy of the hone and continuous high efiiciency of the grinding or abrasive action thereof.

It is, accordingly, a primary object of the present invention to provide an automatic dressing or size control apparatus for abrasive finishing machines and the like for accurately and automatically compensating for the Wear of an abrasive finishing tool during use.

3,056,241 Patented Oct. 2, 1962 Another object of the present invention is to provide an automatic size control apparatus for an abrasive finishing machine which is effective to automatically dress a rotary gear-like honing tool whenever the wear thereof attains a predetermined magnitude so as to prolong the life of the honing tool and concurrently insure continued accurate and efiicient abrasive action of the honing tool with a toothed workpiece.

Still another object of the present invention is to provide a size control apparatus for an abrasive finishing machine which is automatically operative in response to a decrease in the center distance between a gear-like honing tool and a workpiece having tooth elements thereon to effect dressing of the periphery of the honing tool a predetermined increment.

' A further object of the present invention is to provide an automatic size control apparatus for an abrasive finishing machine which is readily integrated with the automatic controlled operating sequence of the machine and is effective to automatically dress a gear-like hone thereon without requiring interruption of the operating cycle of the machine and without requiring any time or attention of the machine operator.

A still further object of the present invention is to provide a size-control apparatus for an abrasive finishing machine which is of simple design, durable and eflicient operation, of economical manufacture, and which can be readily incorporated on and integrated with the operating sequence of the abrasive finishing machine.

Other objects and advantages of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings, wherein:

FIGURE 1 is a perspective view taken of the right front corner of a typical abrasive finishing machine to which the present invention is applicable;

FIG. 2 is a perspective View taken of the rear corner portion of the abrasive finishing machine shown in FIG- URE 1;

FIG. 3 is an enlarged fragmentary perspective view of a gear-like hone disposed in meshing relationship with a work gear at crossed axes and further illustrating the relationship of the dresser head assembly mounted on the spindle housing;

FIG. 4 is a fragmentary transverse side elevation view partly in section and partly in phantom of the abrasive finishing machine shown in FIGURES l and 2 and illustrating in particular, the automatic feed mechanism of the toolhead assembly;

FIG. 5 is a vertical section view of the advancing mechanism for the toolhead assembly as shown in FIG. 4 and taken substantially along line 5-5 thereof;

FIG. 6 is a fragmentary plan view of the dresser head assembly mounted on the spindle housing; and

FIG. 7 is a front elevation view of the dresser head assembly and a fragmentary portion of the spindle housing having an abrasive honing tool rotatably mounted thereon.

Referring now in detail to the drawings and as may be best seen in FIGURES l to 4, an abrasive finishing machine exemplary of those to which the present invention is applicable, broadly comprises a bed 8 employing a reciprocable carriage 10 as shown in phantom in FIG. 4 on which a table 12 is mounted and reciprocable with the carriage longitudinally of the bed. The bed 8 contains a suitable mechanism such as a double-acting fluid actuated cylinder, for example, for reciprocating the carriage whereby a work gear 14 rotatably mounted between a head stock assembly 16 and a tail stock assembly 18 traverses the abrasive tooth elements of a honing tool 20 disposed in tight meshing relationship therewith 3 during a finishing operation. The honing tool 20 is mounted on a tool spindle 22 rotatably mounted in a spindle housing 24. The spindle housing 24 is adjustably and securely mounted on a toolhead assembly 26 whereby the spindle housing 24 can be adjusted to the appropriate angularity to achieve the desired crossed axes relationship between the honing tool 28 and work gear 14.

The toolhead assembly 26 contains a variable speed and reversible drive mechanism therein which is drivingly connected to the tool spindle 22 enabling variation of the rotating speed of the honing tool and providing for reversal in the direction of rotation thereof each time the reciprocating movement of the table 12 is reversed. In this manner both faces of each of the tooth elements on the work gear 14 are quickly and accurately finished to the appropriate dimension and desired surface smoothness.

The toolhead assembly 26 as shown in the exemplary finishing machine illustrated in the drawings, is disposed on a frame or column 28 mounted on the rear of the bed 8 by means of a T-shaped engaging slot 30= and is longitudinally adjustable therealong. Accurate longitudinal adjustment of the column 28 with respect to the center of the table 12 and work gear rotatably mounted thereon is achieved by a rack and pinion mechanism as may be best seen in FIG. 4. The rack and pinion mechanism comprises a shaft 32 rotatably journaled in sleeve bearings in the column housing 34 and is provided with a hexagonal engaging head 36 projecting outwardly of the column housing facilitating engagement and rotation of the shaft 32' by means of a socket wrench, for example. The inner end portion of the shaft 32 is provided with a pinion gear 38 keyed or otherwise fixed-1y secured thereon which is disposed in constant meshing engagement with a gear rack 40 affixed to the rearward portion of the bed 8. In accordance with this arrangement, the column 28 and toolhead assembly 26 thereon is readily adjustable longitudinally of the bed and table in response to rotation of the shaft 32.

The upper surface of the column 28 is provided with a dovetail type projection 42 which is disposed in sliding engagement in a complementarily shaped dovetail groove 44 in a base 46 of the toolhead assembly 26 as may be best seen in FIG. 2. The base 46 is mounted on precision rolls (not shown) for minimizing friction between the toolhead assembly 26 and the column 28 and providing for transverse movement of the toolhead assembly rela tive to the longitudinal axis of the table 12 so as to adjust the appropriate center distance between the honing tool and a work gear.

In a typical finishing operation of a workpiece having tooth elements thereon, the toolhead assembly 26 is trans versely adjusted so as to provide a small clearance such as, for example, about 0.020 inch, between the workpiece and honing tool. The loose meshing relationship between the honing tool and workpiece provided by the clearance facilitates loading and unloading the work gear from between the head stock and tail stock assemblies. At the commencement of the finishing operation, the toolhead assembly and honing tool rotatably mounted at the forward end thereof is advanced toward the work gear by a suitable mechanism such as a counterweight mechanism, for example, to provide for a tight meshing relationship between the honing tool and work gear. The finishing operation thereafter commences and at the completion thereof, the toolhead is again retracted to the clearance position whereby the finished work gear can be easily removed and replaced with a new workpiece to be finished.

An exemplary embodiment of the advancing and retracting mechanism for the toolhead assembly employed in the finishing machine illustrated is best seen in FIG. 4. The transverse movement of the toolhead assembly 26 relative to the column 28 so as to attain the appropriate clearance position between the honing tool thereon and a work gear rotatably mounted on the work table is achieved by a lead screw 48 including a threaded shank portion 50 which is disposed in threaded engagement in a nut 52 secured to the base 46 of the toolhead assembly 26. The projecting end of the lead screw 48 is provided with a hand wheel 54 which is ikeyed thereto for rotating the lead screw which, through the coaction between the threaded shank portion 50 and nut 52, causes the tool head assembly 26 to move transversely of the table in order to accommodate work gears of different diameters.

The portion of the lead screw 48 adjacent to the hand wheel 54 is rotatably and slidably disposed in a pair of sleeve bearings 56a, 56b mounted in a supporting housing 58 which is rigidly affixed to the rear face of the column 28. The lead screw 48' is axially slidable in the sleeve bearings 56a, 56b through a small increment to enable advancement and retraction of the toolhead assembly and the honing tool thereon into and out of tight meshing relationship with the work gear.

Movement of the toolhead assembly from the clearance or retracted position to an advanced or finishing position wherein the honing tool is disposed in tight meshing relationship with the work gear is achieved by a counterweight mechanism comprising a T-shaped bellcrank 60 pivotally mounted on a shaft 62 and having an arm 64 thereon disposed in engaging relationship with a grooved collar 66 pinned or otherwise rigidly affixed to the lead screw 48. The bellcrank 60 includes a second arm 68 having a rod and platform assembly 70 pivotally connected to the outer end thereof on which a desired number of counterweights are placed in accordance with the amount of pressure desired between the tooth elements of the honing tool and the work gear during a finishing operation. The downward pull of the counterweights on the rod and platform assembly 70 is transmitted to the bellcrank 60 through the arm 68 tending to cause the bellcrank to rotate in a clockwise direction as viewed in FIG. 4 which, through the coaction of the arm 64 in engagement with the groove collar 66, causes the toolhead assembly to advance toward the right whereby the honing tool is advanced into tight meshing relationship with the work ear. g Retraction of the toolhead assembly from the finishing position to the clearance position and in opposition to the forward biasing force of the counter-weights 1s achieved by a double acting fluid actuated cylinder 72 having the closed end portion thereof pivotally connected to an ear 74 secured to the side of the column housing 34 and a piston rod 76 thereof pivotally connected to a third arm 78 of the bellcrank 60. Actuation of the cylinder 72, so as to cause the piston rod 76 thereof to be retracted within the cylinder causes the bellcrank 60 to move in a counterclockwise direction as viewed in FIG. 4 whereby the forward biasing force of the counterweights is overcome and causing the lead screw and toolhead assembly engaged thereby to move from the projected position to the clearance position. Movement of the toolhead assembly rearwardly beyond the clearance position is restricted by suitable stop means associated with the lead screw or in the particular exemplary machine shown, by a bottoming of piston in the cylinder 72 having a preselected stroke thereby preventing further rearward axial movement of the lead screw. The advanced or finishing position of the toolhead is established by the point at which the honing tool and work piece are in tight meshing relationship and will gradually increase as the honing tool wears through use. Actuation of the cylinder 72 so as to cause the piston rod 76 thereof to move outwardly of the cylinder, releases the bell crank 68 whereby the counterweights supported on the arm 68 are again effective to cause the toolhead assembly to advance from the clearance position to the finishing position wherein the honing tool thereon is disposed in tight meshing relationship with the work gear.

The length of reciprocating travel of the toolhead assembly 26 between the clearance position and finishing position provides a means of determining the amount of wear of the honing tool and when a dressing thereof is necessary to maintain its dimensional configuration and tfinishing efliciency. The length of reciprocating travel is also directly indicative of the center distance between the honing tool and workpiece. Since the projected or finishing position of the toolhead assembly is determined by the position at which a predetermined pressure exists between the honing tool and the work gear disposed in tight meshing relationship, the gradual wear of the honing tool during use will cause the toolhead assembly to move further outwardly to achieve that pressure causing a greater travel of the toolhead assembly between the finishing position and clearance position, or in other words, the wear of the honing tool causes a progressive decrease in the center distance between the work gear and honing tool. In accordance with the practice of the present invention, the increased stroke of the toolhead assembly, or the decrease in the center distance between the honing tool and work gear, is communicated automatically to the control system of the finishing machine which is conveniently contained in a control cabinet 79 mounted at the right end of the machine (FIG. 1) causing a predetermined dressing of the honing tool and concurrently advancing the toolhead assembly to a new clearance position disposed closer to the work gear.

The honing tool which is of a gear-like configuration and is employed for finishing the tooth elements on the work gear disposed in meshing relationship therewith is comprised of a plurality of tooth elements conjugate to the form of the tooth elements on the workpiece. The honing tools conventionally employed are of the socalled resinoid bonded type wherein a desired quantity of a variety of conventional abrasive grains or mixtures thereof having the appropriate grit size and hardness are imbedded in a synthetic resinous material providing therewith the desired abrasive finishing or honing action and the desired degree of smoothness of the finished surface. The abrasive action between the honing tool and the tooth elements on the workpiece automatically maintains the appropriate profile of the abrasive tooth elements on the honing tool. However, the thickness of the tooth elements on the honing tool decreases during use and the root or bottom of the honing tool along the clearance circle of the honing tool is decreased as a result of a gumming-out of this area by the tips of the tooth elements on the workpiece causing a corresponding decrease in the pitch circle of the honing tool. Accordingly, by dressing the outside diameter of the honing tool in accordance with the practice of the present invention, the appropriate pitch-circle relationship and tooth thickness of the honing tool is restored and eificient abrasive action is maintained between the work gear and honing tool.

Communication of the decrease in the center distance between the honing tool and the work gear as occasioned by the progressive wear of the honing tool is achieved in accordance with one exemplary embodiment of this invention as illustrated in the drawings by means of a disk or plate 80 affixed to the projecting end of the lead screw 48 adjacent to the hand wheel 54 which is adapted to trip a sensing device, such as a limit switch 82, adjustably aifixed to the supporting housing 58 at such time when a predetermined reduction in the center distance occurs and which, upon being tripped, signals the control circuit of the finishing machine so as to cause concurrent advancement of the toolhead assembly and dressing of the honing tool.

Advancement of the toolhead assembly in response to actuation of the sensing device 82 by the disk 80 is achieved through a ratchet mechanism as may be best seen in FIGS. 4 and 5, comprising a rotary ratchet wheel 84 which is splined to the lead screw 48 and axially slidable relative thereto. The ratchet wheel 84 and lead screw to which it is aifixed is rotated at predetermined increment by means of a ratchet pawl 86 pivotally connected to a slide member 88 slidably disposed in a cylindr'ical housing 98 which forms an integral part of the supporting housing 58. The slide member 88 and ratchet pawl 86 thereon is reciprocablle in a direction transversely of the axis of the lead screw to and from an advanced position and a retracted position.

Movement of the slide member 88 from a retracted position as shown in FIG. 5 to the advanced position is achieved by a fluid actuated cylinder 92 having a piston rod 94 thereof disposed in adjustable threaded engagement with the slide member 88. During the advancing movement of the slide member 88, the engaging tooth 96 on the ratchet pawl 86 engages a ratchet tooth 98 on the ratchet wheel 84 causing the ratchet wheel and lead screw to concurrently rotate through a predetermined arcuate movement. Movement of the slide member 88 from the projected position to the retracted position can be achieved by the cylinder 92, or in the case of a single acting cylinder as shown in FIG. 5, by means of a helical compression spring 180- having one end thereof seated against the end of the slide member 88 and the other end thereof against a head portion 102 of the cylindrical housing 90.

The maximum reciprocating movement of the slide member 88 to achieve the desired incremental rotation of a ratchet wheel 84 is adjustably regulated by a stop screw 104 threadably engaged in the head portion 102 and axially disposed within the compression spring 100. The shank end portion of the stop screw 104 is adapted to abut the end of the slide member 88 when the fully projected position is attained.

To assure positive engagement of the engaging tooth 96 on the ratchet pawl 86 and a ratchet tooth 98 on the ratchet wheel 84, a suitable compression spring 106 is employed for biasing the ratchet pawl in a clockwise direction as viewed in FIG. 5 and in firm engaging relationship with the periphery of the ratchet wheel 84 during the advancing movement of the slide member. When in the fully retracted position, the ratchet tooth 96 is withdrawn out of engagement with the ratchet teeth 98 on the ratchet wheel. Inadvertent drift of the lead screw is prevented by a resiliently biased brake 107 disposed in frictional contact against the face of the ratchet wheel 84.

The length of the advancing stroke of the slide member 88 is adjustable and depends on such related factors as the radius of the ratchet wheel 84, the pitch or lead of the threads on the threaded shank portion 50 on the lead screw 48, and the advancing increment through which it is desired to advance the toolhead assembly 26 toward the table 12. As a typical example, the ratchet assembly can be so arranged to cause an advancement of the toolhead assembly in an amount of 0.001 inch each time the sensing device 82 is tripped by the disk 80. Concurrently, the honing tool is also dressed an appropriate amount.

By virtue of the ratchet advancement of the lead screw 48 and a corresponding adjusted decrease in the center distance between the honing tool and work gear, the reciprocating travel of the tool-head assembly and lead screw threadably engaged thereto between the clearance position and finishing position is incrementally decreased whereby the disk is moved to the left as viewed in FIG. 4 and out of contact with the sensing device 82 when the toolhead assembly is in the finishing position. As further wear of the honing tool occurs, the clearance between the disk 88 and the sensing device 82 progressively decreases until the sensing device is again actuated causing another incremental advancement of the toolhead assembly by the incremental rotation of the lead screw.

It will be appreciated by those skilled in the art that satisfactory operation of the ratchet mechanism can also be achieved by a solenoid, for example, or an engageable and disengageable motor driven worm drive assembly which are effective to cause incremental rotation of the lead screw.

As heretofore stated, the tripping of sensing device 82 by the disk 80 in addition to causing advancement of the lead screw concurrently causes the honing tool to be dressed a predetermined amount. A dressing of the honing tool is achieved by a dresser head assembly 103 including a housing frame 110 which is securely mounted at the upper portion of the spindle housing 24 as may be best seen in FIGS. 6 and 7. A feed spindle 112 having screw threads along the lower portion thereof is threadably engaged in a threaded bore 114- extending through the housing frame 110 and is provided at the lower projecting end thereof with an abrasive disk or dresser 116 which is adapted to contact the periphery of the honing tool and abrasively remove a controlled quantity thereof as the honing tool is rotated. The lower face of the dresser 116 disposed adjacent the periphery of the honing tool 20 is provided with an abrasive layer 117 comprising a plurality of hard abrasive grains such as diamond grit, for example, which is effective to abrade or dress the abrasive periphery of the honing tool 20. The dresser is provided with a grooved shank 118 which is disposed in an axial bore 120 in the base of the feed spindle 112 and is removably secured therein by means of a set screw 122.

The upper end of the feed spindle 112 is provided with a finger wheel 124- providing for manual rotation of the feed spindle 112 to cause the feed spindle and dresser 116 mounted thereon to he radially adjusted relative to the periphery of the honing tool 20.

Automatic controlled incremental movement of the feed spindle 112 and dresser 116 thereon in response to actuation of the sensing device 82 is achieved by a ratchet drive mechanism having a construction and operating sequence similar to the ratchet mechanism employed for incrementally advancing the lead screw 48. As shown in FIGS. 6 and 7, the ratchet mechanism in the dresser head assembly 108 comprises a double acting, or single acting spring-return fluid actuated cylinder 126 mounted on the housing frame 110 and including a rod 128- which is disposed in axial alignment with a bore 130 extending through the upper portion of the housing frame 110. A slide member 132 is slidably disposed in the bore 130 and is adjustably and threadably secured to the threaded end portion of the rod 128 and reciprocable thereby to and from an advanced position and a retracted position. The maximum reciprocating movement of the slide member 132 is controlled by a stop screw 134 threadably engaged in a head member 136 secured to the housing frame 110.

The slide member 132 includes a ratchet pawl 138 pivotally mounted in a recessed portion of the slide member 132 and is resiliently biased by means of a spring 140 into engaging relationship with the periphery of a ratchet wheel 142 affixed to the feed spindle 112. In accordance with this arrangement, each time the slide member 132 is reciprocated by the cylinder 126, the coaction between the ratchet pawl 138 and the ratchet wheel 142 causes a controlled incremental arcuate movement of the feed spindle 112 whereby the dresser 11 6 is advanced in a direction radially inwardly of the axis of rtation of the honing tool 20 providing an incremental dressing of the periphery of the honing tool. As a typical example, the feed spindle can be provided with a 16 pitch left-hand thread which through the controlled reciprocating movement of the slide member causes the feed spindle to be rotated six degrees on each advancing movement thereof effecting a 0.001 inch radial movement of the dresser with a corresponding 0.001 inch removal of material from the periphery of the honing tool. To prevent over-travel of the feed spindle 112 when actuated and to avoid rotational drift thereof during machine operation, a friction brake assembly is preferably incorporated in the dresser head assembly which frictionally bears against the feed spindle shaft preventing inadvertent rotation thereof. The friction brake assembly comprises a bore 144 as may be best seen in FIG. 6, having one end thereof in communication with the feed spindle 112 in which a brake plunger 146 is slidably disposed and resiliently biased into bearing contact with the periphery of the feed spindle by means of a coil spring 148. The coaction between the brake plunger 146 and feed spindle 112 frictionally restrains the feed spindle from inadvertent movement.

While it will be apparent that the embodiments of the invention herein disclosed are well calculated to fulfill the objects of the invention, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope or fair meaning of the subjoined claims.

What is claimed is:

1. In an abrasive finishing machine including a gearshaped honing tool rotatably mounted on a toolhead and relatively biased into tight meshing relationship with a rotatable toothed workpiece to be finished, the improvement comprising a dressing mechanism for automatically dressing the honing tool in response to a predetermined decrease in the center distance between the honing tool and workpiece, said dresser mechanism comprising sensing means for sensing the decrease in said center distance resulting from wear of the honing tool, dresser means actua-ble in response to said sensing means for dressing the periphery of the honing tool and causing a reduction in the diameter thereof, and compensating means associated with said sensing means for compensating the decrease in said center distance caused by the dressing of the honing tool.

2. In an abrasive finishing machine including a gearshaped honing tool rotatably mounted on a tool head and relatively biased into tight meshing relationship with a rotatable toothed workpiece to be finished, the improvement comprising a dressing mechanism for automatically dressing the honing tool in response to a predetermined decrease in the center distance between the honing tool and workpiece, said dresser mechanism comprising presettable means for sensing a predetermined incremental decrease in said center distance, cutting means disposed adjacent the periphery of the honing tool, means actuable in response to said presettable means for moving said cutting means toward the honing tool to effect a dressing and incremental reduction in the diameter of the honing tool, and compensationg means for resetting said presettable means after each dressing of the honing tool to compensate for the decrease in said center distance resulting from the decrease in diameter of the honing tool produced by the dressing.

3. In an abrasive finishing machine including a gearshaped honing tool rotatably mounted on a toolhead and relatively biased into tight meshing relationship with a rotatable toothed workpiece to be finshed, the improvement comprising a dressing mechanism for automatically dressing the honing tool in response to a predetermined decrease in the center distance between the honing tool and workpiece, said dresser mechanism comprising presettable means for sensing a predetermined incremental decrease in said center distance, a dresser head disposed adjacent to the honing tool and including a frame, a cutter spindle disposed in rotatable threaded engagement on said frame, a cutter on said cutter spindle disposed adjacent to the periphery of the honing tool, and ratchet means for rotating and advancing said cutter spindle and said cutter thereon toward the honing tool, said ratchet means actuable in response to said presettable means for causing a dressing of the periphery of the honing tool, and compensating means for resetting said presettable means after each dressing of the honing tool to compensate for the decrease in center distance resulting from the decrease in diameter of the honing tool produced by the dressing.

4. In an abrasive finishing machine including a gear- 7 shaped honing tool rotatably mounted on a toolhead and relatively biased into tight meshing relationship with a rotatable toothed workpiece to be finished, the improvement comprising a dressing mechanism for automatically dressing the honing tool in response to a predetermined decrease in the center distance between the honing tool and workpiece, said dresser mechanism comprising presettable means for sensing a predetermined incremental decrease in said center distance, a dresser head disposed adjacent the honing tool and including a frame, a cutter spindle disposed in rotatable threaded engagement on said frame, a cutter on said cutter spindle disposed adjacent to the periphery of the honing tool, a ratchet wheel afi'ixed to said cutter spindle, engaging means disposed adjacent to said ratchet wheel and reciprocable longitudinally thereof to and from an advanced position and a retracted position, means for reciprocating said engaging means, said engaging means operative during the advancing movement thereof to engage said ratchet wheel and rotate and advance said cutter spindle and said cutter thereon toward the honing tool, said drive means actuable in response to said presettable :means for reciprocating said engaging means, and compensating means for resetting said presettable means after each dressing of the honing tool to compensate for the decrease in said center distance resulting from the decrease in diameter of the honing tool produced by the dressing.

5. In an abrasive finishing machine including a gearshaped honing tool rotatably mounted on a toolhead and relatively biased into tight meshing relationship with a rotatable toothed workpiece to be finished, the improvement comprising a dressing mechanism for automatically dressing the honing tool in response to a predetermined decrease in the center distance between the honing tool and workpiece, said dresser mechanism comprising presettable means for sensing a predetermined incremental decrease in said center distance, a dresser head disposed adjacent to the honing tool and including a frame, a cutter spindle disposed in rotatable threaded engagement on aid frame, a cutter on said cutter spindle disposed adjacent to the periphery of the honing tool, a ratchet wheel on said cutter spindle, a slide member on said frame reciprocable longitudinally of said ratchet wheel, a pawl pivotally mounted on said slide member and biased into engaging relationship with said ratchet wheel, a fluid actuated cylinder connected to said slide member for reciprocating said slide member to and from a retracted position and an advanced position, said cylinder actuable in response to said presettable means for reciprocating said slide member and said pawl thereon for rotating said cutter spindle and said cutter thereon through a predetermined areuate increment effecting a dressing of the periphery of the honing tool, and compensating means for resetting said presettable means after each dressing of the honing tool to compensate for the decrease in said center distance resulting from the decrease in diameter of the honing tool produced by the dressing.

6. In an abrasive finishing machine including a gearshaped honing tool rotatably mounted on a toolhead and relatively biased into tight meshing relationship with a rotatable toothed workpiece to be finished, the improvement comprising a dressing mechanism for automatically dressing the honing tool in response to a predetermined decrease in the center distance between the honing tool and workpiece, said dresser mechanism comprising presettable means including sensing means adjustably mounted on the machine, and actuator means disposed in variable spaced relationship from said sensing means and movable in relationship with said center distance between the honing tool and workpiece, said actuator means operable to trip said sensing means on a predetermined incremental decrease of said center distance, cutting means disposed adjacent the periphery of the honing tool, means actuable in response to the tripping of said sensing means for moving said cutting means toward the honing tool and etfecting a dressing and incremental reduction in the diameter thereof, and compensating means for retracting said actuator means in appropriate spaced relationship from said. sensing means to compensate for the decrease in said center distance resulting from the decrease in diameter of the honing tool produced by the dressing.

7. In a tool dresser mechanism for an abrasive machine for finishing tooth elements; the combination comprising a frame including means for rotatably mounting a toothed workpiece thereon, a toolhead on said frame including a gear-shaped abrasive honing tool rotatably and drivingly mounted thereon, said toolhead movable laterally of the axis of rotation of the workpiece to and from a clearance position wherein said tool is disposed in spaced relationship from the workpiece and a finishing position wherein said tool is disposed in tight meshing relationship with a workpiece, means for moving said toolhead between said clearance position and said finishing position, adjusting means for positioning said toolhead in said clearance position, presettable means for sensing a predetermined incremental increase in the travel distance of said toolhead between said clearance and said finishing positions caused by the wear of said tool, dresser means actuable in response to said presettable means for dressing the periphery of said tool and causing an incremental reduction in diameter thereof, and compensating means associated with said adjusting means for advancing the clearance position of said toolhead toward the workpiece an increment corresponding substantially to the increment removed from the periphery of said tool by the dressing thereof.

8. In a tool dresser mechanism for an abrasive machine for finishing tooth elements; the combination comprising a frame including means for rotatably mounting a toothed workpiece thereon, a toolhead on said frame including a gear-shaped abrasive honing tool rotatably and drivingly mounted thereon, said toolhead movable laterally of the axis of rotation of the workpiece to and from a clearance position wherein said tool is disposed in spaced relationship from the workpiece and a finishing position wherein said tool is disposed in tight meshing relationship with a workpiece, urging means for biasing the toolhead and said tool thereon toward said finishing position, retracting means for retracting said toolhead to said clearance position, adjusting means coacting with said toolhead for adjusting said clearance position thereof, presettable means for sensing a predetermined incremental increase in the travel distance of said toolhead between said clearance and said finishing positions as occasioned by the wear of said tool, dresser means actuable in response to said presettable means for dressing the periphery of said tool and causing a predetermined reduction in the diameter thereof, and compensating means associated with said adjusting means for advancing said toolhead toward the workpiece an increment corresponding substantially to the increment removed from the periphery of said tool by the dressing thereof and effecting a resetting of said presettable means.

9. In a tool dresser mechanism for an abrasive machine for finishing tooth elements; the combination comprising a frame including means for rotatably mounting a toothed workpiece thereon, a toolhead on said frame including a gear-shaped abrasive honing tool rotatably and drivingly mounted thereon, said toolhead movable laterally of the axis of rotation of the workpiece to and from a clearance position wherein said tool is disposed in spaced relationship from the workpiece and a finishing position wherein said tool is disposed in tight meshing relationship with a workpiece, urging means for biasing the toolhead and said tool thereon toward said finishing position, retracting means for retracting said toolhead to said clearance postion, adjusting means coacting with said toolhead for adjusting said clearance position thereof and including screw means slidably mounted on said frame and threadably engaged in said toolhead, and stop means associated with said screw means and said frame for restricting rearward movement of said toolhead beyond the adjusted said clearance position, sensing means and actuator means associated with said frame and said screw means disposed in variable spaced relationship and relatively movable in relationship to the movement of the said toolhead relative to the workpiece, said actuator means operable to trip said sensing means on a predetermined incremental increase in the travel distance of said toolhead between said clearance and said finishing position caused by the wear of said tool, dresser means actuable in response to said sensing means for dressing the periphery of said tool and causing an incremental reduction in the diameter thereof, and compensating means associated with said screw means for advancing said clearance position of said toolhead toward the workpiece an increment corresponding substantially to the increment removed from the periphery of said tool by the dressing thereof.

10. In a tool dresser mechanism for an abrasive machine for finishing tooth elements; the combination comprising a frame including means for rotatably mounting a toothed workpiece thereon, a toolhead on said frame including a gear-shaped abrasive honing tool rotatably and drivingly mounted thereon, said toolhead movable laterally of the axis of rotation of the workpiece to and from a clearance position wherein said tool is disposed in spaced relationship from the workpiece and a finishing position wherein said tool is disposed in tight meshing relationship with a workpiece, urging means for biasing the toolhead and said tool thereon toward said finishing position, retracting means for retracting said toolhead to said clearance position, adjusting means coacting with said toolhead for adjusting said clearance position thereof and including screw means slidably mounted on said frame and threadably engaged in said tooihead, and stop means associated with said screw means and said frame for restricting rearward movement of said toolhead be yond the adjusted said clearance position, sensing means and actuator means associated with said frame and said screw means disposed in variable spaced relationship and relatively movable in relationship to the movement of the said toolhead relative to the workpiece, said actuator means operable to trip said sensing means on a predetermined incremental increase in the travel distance of said toolhead between said clearance and said finishing position caused by the wear of said tool, dresser means actuable in response to said sensing means for dressing the periphery of said tool and causing an incremental reduction in the diameter thereof, and compensating means associated with said screw means for advancing said clearance position of said toolhead toward the workpiece an increment corresponding substantially to the increment removed from the periphery of said tool by the dressing thereof, said compensating means comprising ratchet means for rotating said screw means through a predetermined arcuate movement and advancing said clearance position of said toolhead a predetermined increment toward the workpiece.

11. In a tool dresser mechanism for an abrasive machine for finishing tooth elements; the combination comprising a frame including means for rotatably mounting a toothed workpiece thereon, a toolhead on said frame including a gear-shaped abrasive honing tool rotatably and drivingly mounted thereon, said toolhead movable laterally of the axis of rotation of the workpiece to and from a clearance position wherein said tool is disposed in spaced relationship from the workpiece and a finishing position wherein said tool is disposed in tight meshing relationship with a workpiece, means for moving said toolhead between said clearance position and said finishing position, adjusting means for positioning said toolhead in said clearance position, presettable means for sensing a predetermined incremental increase in the travel distance of said toolhead between said clearance and said finishing positions caused by the wear of said tool, a dresser head including cutter means disposed adjacent to said tool and including first ratchet means thereon actuable in response to said presettable means for advancing said cutter means toward said tool causing an incremental reduction in the diameter thereof, and compensating means associated with said adjusting means including second ratchet means actuable in response to said presettable means for advancing the clearance position of said toolhead toward the workpiece an increment corresponding substantially to the increment removed from the periphery of said tool by the dressing thereof.

References Cited in the file of this patent UNITED STATES PATENTS 1,183,020 Maag May 16, 1916 2,627,141 Praeg Feb. 3, 1953 2,942,389 Praeg et al. June 28, 1960 

